The goal of this program is to determine whether a new class of sensor that measures electric potentials off the body at the microvolt level can provide a signal for pediatric ECG monitoring that is equivalent or better than a conventional, skin-contacting electrode. There are a number of important benefits of using this new technology for monitoring biopotentials in general, and these benefits are particularly significant for infants. Prior clinical measurements have been on adults, so Phase I we will first define electrode placement and mounting issues suitable for infants and children. We will also develop a rapid methodology to confirm correct operation to aid in putting on the electrodes. The principal Phase I activity will be to conduct a preliminary evaluation of the utility of the new electrode technology for routine pediatric electrocardiography on infants, using off-body electrodes in pockets sewn onto the outside of a "bunny suit". We will also conduct a separate initial assessment of ambulatory monitoring using sensors in pockets on the outside of a T-shirt. The methodology will be to conduct a simultaneous measurement with conventional, skin-contacting electrodes in the same single lead configuration to control for any patient-to-patient variation. In Phase II, more sophisticated studies will be performed to quantify the system performance in the presence of other medical devices and when operating through bandages. The trade-off between signal quality and electrode size, and pressure on the skin, will be quantified, and packaging will be developed to enable the electrodes to withstand standard hospital laundering. Based on these results, a system will be designed for pediatric monitoring applications. The culmination of Phase II will be a 50-subject clinical trial of the technology on infants and children.